JP4906591B2 - Position detection device - Google Patents

Description

  The present invention relates to a position detection technique, and more particularly to a position detection technique that can always detect a position with high accuracy.

  As a position detection device, GPS that detects the position using radio waves from artificial satellites, a position detection device that uses radio wave transmission time or electric field strength from multiple wireless LAN base stations or mobile phone base stations, and uses infrared rays Various position detecting devices such as the position detecting device have been developed.

  A position detection device using GPS can detect a position with an accuracy of an error of 10 meters or less anywhere in the world in a place where radio waves from GPS satellites can be received satisfactorily. However, GPS satellite radio waves may not be received near large buildings, in buildings, or underground shopping centers, or position detection errors may increase due to multipath effects, and position detection itself may not be possible.

  A position detection device using radio waves of a wireless LAN developed mainly for indoor position detection uses the principle of three-point surveying. Therefore, if radio waves from three or more wireless LAN base stations can be received, the position can be detected with an accuracy of several meters or less. However, in areas where radio waves can be received only from three or less base stations, or areas where there is no wireless LAN infrastructure, the accuracy is reduced, or position detection itself is not possible.

  Thus, an apparatus that seamlessly detects positions using a plurality of position detection apparatuses has been proposed. For example, in Patent Document 1, the priority order is determined based on the general accuracy of the position detection device, and when the position is detected by a plurality of position detection devices, the position detection device with the highest priority order is used. The output value is output as the position detection result.

Japanese Patent Laid-Open No. 2004-228688 shows that the position detection device having the highest accuracy is selected based on the accuracy of the position detection device notified by each position detection device.
JP-A-10-281801 JP 2001-235528 A

  In the technique disclosed in Patent Document 1, a value output from a position detection device with the highest priority is output as a position detection result. For this reason, even when a position can be detected by a plurality of position detection devices, a highly accurate position can be output. However, the priority order is determined based on the general accuracy of the position detection device. For example, the general accuracy of a position detection device using GPS is about a few dozen meters.

  However, the accuracy is a value at a place where the sky is opened. As described above, in the vicinity of a building or the like, detection is often possible only with position accuracy far inferior to general accuracy due to the influence of radio wave shielding or multipath. For this reason, the result detected by the position detection device having a lower priority than GPS may have higher accuracy.

  In the technique disclosed in Patent Document 2, it is possible to determine the superiority or inferiority of accuracy based on accuracy information from the position detection device. However, similar to the technique disclosed in Patent Document 1, it is not possible to cope with a change in accuracy depending on a place where the position detection device is placed.

  The present invention has been made in view of these problems, and can evaluate the accuracy of a plurality of absolute position detection devices and output the detection output of the most accurate absolute position detection device as a position detection result. It provides position detection technology.

  In order to solve the above problems, the present invention employs the following means.

A plurality of types of absolute position detection devices that detect a plurality of signals radiated from known positions and detect their own absolute position, and a relative that detects the amount of movement of itself within a predetermined period as a change in the relative position of itself The degree of similarity between the position detection device and the relative position change trajectory within the predetermined period and the absolute position change detected by the absolute position detection device within the predetermined period is calculated for each of the various absolute position detection devices. a similarity calculation unit which, among the plurality of kinds of absolute position sensing device, e Bei an output switching unit for selecting and outputting the output of the absolute position detecting apparatus having the greatest similarity, the similarity calculating unit calculates When the similarity is less than or equal to a preset threshold, the output of the relative position detection device with the detection output of the absolute position detection device immediately before the similarity becomes less than or equal to the threshold as an initial value is used as the position detection device. With the detection output, thereby lowering the threshold over time.

  Since the present invention has the above configuration, it is possible to evaluate the accuracy of a plurality of absolute position detection devices and output the detection output of the most accurate absolute position detection device as a position detection result.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a position detection device 13 according to the present embodiment. In FIG. 1, 8 is an absolute position detector. The absolute position detection device is a device that receives a signal such as an electromagnetic wave, light, or an ultrasonic wave transmitted from a known position, and directly detects the position using the received signal. As an absolute position detecting device, a GPS receiving device using satellite positioning 1, a wireless LAN position detecting device 2 using a wireless LAN base station, a position detecting device 3 using a mobile phone using a mobile phone base station, an infrared transmitter Infrared position detection device using the. In addition to this, it is possible to use a position detection device using an ultrasonic transmitter, or a device that detects a position based on ID information read, such as an RFID.

  The absolute position detection device can detect the position with high accuracy in a place where the signal from the transmitter can be directly received. However, the accuracy is lowered in a place where the signal is reflected by the shielding object or the signal is attenuated by the shielding object. That is, the position accuracy can be estimated in a space without an obstruction. However, it is difficult to predict signal propagation in a normal space where there is an obstacle, and it is difficult to estimate position accuracy with the position detection device alone.

  Reference numeral 7 denotes a relative position detection device. The relative position detection device can be constituted by an inertial navigation device 5, for example. The relative position detection device is a device that detects a speed and a traveling direction and detects a change in relative position by time integration. For example, in the inertial navigation apparatus 5, the speed and the traveling direction can be detected by a built-in acceleration sensor or gyro sensor, and the relative position can be detected by integration processing based on the starting point.

Other examples of the relative position detection device include (1) a method widely used in a car navigation system and the like that detects a moving speed from a vehicle speed pulse and detects a direction using a gyro,
(2) The road texture is read with a camera etc., and the speed and direction of travel are obtained from the flow of the texture. (3) The 3D information of the wall and ground is read with the laser radar, For example, a method of detecting the speed and direction of movement rather than movement.

  The relative position detection device can detect the relative position with high accuracy based on the departure point for a short time. However, as time passes, errors accumulate and accuracy decreases.

  A similarity calculation unit 14 calculates the similarity between the movement trajectory obtained by each of the absolute position detection devices 1 to 4 and the movement trajectory obtained by the relative position detection device 7. As will be described later, the similarity is calculated by, for example, the movement locus obtained by the absolute position detection device (for example, 35a in FIG. 3) and the movement locus obtained by the relative position detection device (for example, 37a in FIG. 3) in the calculation target section. Can be calculated as the accumulation of deviations between the two trajectories obtained when the tangent vectors of the trajectories are overlapped at the starting point of the target section (35, 37 in FIG. 3).

  Reference numeral 9 denotes a switching signal generation unit, and based on the calculated similarity, a switching signal that determines whether the position information detected by the absolute position detection devices 1 to 4 or the relative position detection device 5 is output. Generate. Reference numeral 15 denotes a switching unit that selects one of outputs from the absolute position detection devices 1 to 4 and the relative position detection device 5 as an output based on the switching signal.

  Reference numeral 6 denotes a display unit that displays the output position information superimposed on a map or the like. 11 is a communication device, and transmits the detected position information to an external device using a communication line. Reference numeral 10 denotes a communication device for receiving a transmitted signal. A management terminal 12 manages the position or movement trajectory of the person wearing the position detection device 13 based on the received signal.

  FIG. 2 is a diagram for explaining the processing of the similarity calculation unit and the processing of the position output switching unit. When the process is started (step S20), position information is acquired using each position detection device (absolute position detection devices 1 to 4 and relative position detection device 5). The time at which the position information is acquired is preferably the same time for the subsequent evaluation of the similarity of the position information. However, interpolation processing may be performed based on the previous and subsequent acquired data to obtain data at the same time (step S21). ). Next, the latest data is added to the history data of each position detection device and the oldest data is deleted. As a result, it is possible to acquire history data having a certain time width used for evaluating the similarity of position information (step S22). Next, using the history data created in step 22, the similarity between the history data of the position information detected by the relative position detector 7 and the history data detected by each of the absolute position detectors 1 to 4 is calculated (step S23).

  Here, FIG. 3 is a diagram illustrating a position detection result by a GPS that is a representative of the absolute position detection device, and a position detection result by an inertial navigation device that is a representative of the relative position detection device. In FIG. 3, reference numeral 38 denotes a movement route actually moved. Reference numeral 30 denotes a movement trajectory detected using GPS. Reference numeral 31 denotes a movement locus detected using an inertial navigation device. Note that the initial position of the inertial navigation apparatus is initialized using position information and direction information obtained by GPS at the starting point 32.

  Sections with good position accuracy by GPS 1 are 33, 34, and 35, and in this section, a movement locus that substantially matches the actual movement path 38 is detected. In a section other than the above, the movement trajectory is displayed, but the position accuracy is poor due to the influence of multipaths, and a movement path different from the actual movement path is detected.

  The movement route 31 obtained by the inertial navigation apparatus 5 shows a movement locus that substantially matches the actual route in the vicinity of the starting point, but the error accumulates with time and the position accuracy decreases, and it is considerably close to the end point. The error is occurring. However, the movement trajectory 36a obtained by the inertial navigation device 5 in the same section 36 at the same time as the movement trajectory 34a obtained by GPS in the section 34 with high accuracy by GPS, and the movement obtained by GPS in the section 35 with high precision by GPS. It can be seen that the movement trajectories 37a obtained by the inertial navigation device 5 in the same section 37 at the same time as the trajectory 35a have similar movement trajectory shapes.

  That is, when the position detection method using the relative position detection device is used, an error is accumulated because the integration process is performed from the starting position. For this reason, the error is large when comparing only the current position information. However, when comparing the movement trajectories in the short period (for example, sections 34 and 36), the shapes of the movement trajectories are similar except for the rotation of the movement trajectory based on the azimuth error. That is, in a short period, the accuracy of the relative position detection device can be evaluated by comparing the movement locus detected by the absolute position detection device and the movement locus detected by the relative position detection device, excluding rotation.

  FIG. 4 is a diagram for explaining the similarity of movement trajectories obtained in this way. The example of FIG. 4 is an example when moving from an outdoor location where the GPS receiver can be used well to an indoor location where the GPS receiver is not available, and finally moving on a path moving outdoors where the GPS receiver can be used satisfactorily. . In addition, in the said indoors, the environment where the position detection apparatus by wireless LAN or the position detection apparatus by infrared rays can be utilized is assumed. In addition, it is assumed that the mobile phone can be used for communication and position detection by a base station of the mobile phone can be used.

  In FIG. 4, the horizontal axis represents the elapsed time during movement, and the vertical axis represents the degree of similarity or position accuracy. The similarity and the position accuracy indicate that the similarity and the position accuracy increase as the value increases.

  In FIG. 4, a line 40 indicates the similarity between the movement locus by the GPS receiver 1 and the movement locus by the relative position detection device 7. Similarly, a line 41 indicates the similarity between the movement locus of the mobile phone by the position detection device 3 and the movement locus of the relative position detection device 7. A line 42 indicates the similarity between the movement locus by the wireless LAN position detection device 2 and the movement locus by the relative position detection device 7. A line 43 indicates the similarity between the movement locus by the infrared position detection device 4 and the movement locus by the relative position detection device 7.

  As shown by the line 40, the similarity between the movement locus by the GPS receiver 1 and the movement locus by the relative position detection device 7 is high outdoors but low indoors. Further, the similarity of the movement trajectory by the wireless LAN position detection device 2 and the relative position detection device 7 and the similarity of the movement trajectory by the infrared position detection device 4 and the relative position detection device 7 are high only in a limited indoor area. You can see that

  Returning to FIG. 2, the similarities of the absolute position detection devices calculated in step S <b> 23 of FIG. 2 are compared, and the position information of the absolute position detection device showing the highest similarity is used as the position information at the current position. Select (step S24).

  Line 44 in FIG. 4 is the result of the selection. As shown in the figure, the absolute position detection device output indicating the maximum similarity is selected and output for each area. That is, the accuracy of a plurality of absolute position detection devices can be evaluated, and the detection output of the most accurate absolute position detection device can be output as the position detection result. As is clear from the above description, the “similarity” has the same meaning as the “position accuracy” of the position detected by the position detection device.

  As described above, the line 44 is a result of acquiring the position while switching the position information with the highest accuracy of the available absolute position detection device. However, since there is no absolute position detection device that can provide high position accuracy in the section of the region 45, the position accuracy remains low. Therefore, in steps S25 and S26 of FIG. 2, it is considered to interpolate this section using the output of the relative position detection device.

  First, it is determined whether or not the degree of similarity of the absolute position detection device selected in step 24 exceeds a preset threshold value (step S25). Although the threshold value varies depending on the accuracy required by the application to be used, in the present embodiment, the threshold value is designated as a broken line 46. If the degree of similarity is higher than the threshold, the accuracy of the absolute position detection device is high, so the process proceeds to step 27, and the position information selected in step S24 is output as it is (step S28). If the threshold value is not exceeded, the accuracy is lowered, and the process proceeds to step 26.

  In step 26, the position detection process is performed using the relative position detection device with the last position where the similarity exceeds the threshold as an initial value. That is, the position of the last point 49 that has exceeded the threshold value in FIG. 4 is determined as the initial position by the integration processing in the speed and traveling direction, and the determined position is output as position information (step S26).

  A line 47 in FIG. 4 represents the final accuracy of the position information output in step 28. Here, a section indicated by a broken line 48 is a section interpolated using the relative position detection device. The accuracy of the relative position detecting device decreases with time due to an integration error. However, it can be seen that the accuracy is kept high as compared with the accuracy in the region 45.

  The detected position information can be displayed on the map displayed on the display unit 6 or transmitted to the remote management terminal 12 using the communication device 11 (step S28). Thereafter, the processing from step 21 is repeated, and position information that changes every moment can be collected with high accuracy.

  FIG. 6 is a diagram illustrating an example in which the threshold value when changing between the absolute position detection device and the relative position detection device is variable.

  In the examples so far, the threshold value (switching threshold value) 46 when switching between the absolute position detection device and the relative position detection device is fixed. However, the position detection output by the relative position detection device deteriorates with time. That is, as shown in FIG. 6A, when the switching threshold value 51 is a fixed value, the output from the absolute position detection device is switched to the relative position detection device at time 52, and then the accuracy of the relative position detection device deteriorates with time. For this reason, in the region 53, the output of the relative position detection device is output because the output of the absolute position detection device is lower than the fixed threshold 51 even though the accuracy of the relative position detection device is higher. It will be.

  Therefore, as shown in FIG. 6B, the threshold value after time 52 when the absolute position detection device is switched to the relative position detection device is set as a threshold 55 that decreases with time. This threshold value is a predicted value of the accuracy of the relative position detection device. As a result, the point at which the relative position detection device is switched to the absolute position detection device is a time point 54, and the accuracy is improved.

  FIG. 5 is a diagram illustrating an example when the position detection device is carried by a pedestrian. The pedestrian 50 has a portable terminal 56 and a relative position detection device 55 (for example, an inertial navigation device). The portable terminal 56 has a function of detecting a position by receiving radio waves from the GPS satellite 51, a function of detecting a position by using radio waves of the wireless LAN 52, and a position by using the radio waves of the mobile phone base station 53. It incorporates an absolute position detection device such as a detection function and a function of receiving a signal from the infrared transmitter 54 and detecting a position. The accuracy of the absolute position detection device built in the portable terminal 56 is evaluated based on the output result of the relative position detection device attached to the waist, for example, and the most accurate position information is output on the screen of the portable terminal 56. It can be displayed and used for navigation.

  Although FIG. 5 shows an example in which a pedestrian is carried, the present invention can also be applied when detecting the movement of a car or a robot. In the case of a robot that moves on wheels, the inertial navigation device 55 can also use a method for obtaining a moving distance not by acceleration but by the number of rotations of the wheel.

  In addition, although GPS has been described as an example of the satellite positioning device, the present invention can also be applied to a case where a satellite positioning device such as GLONASS or Galileo is used in addition to GPS. GLONASS and Galileo move in different orbits than GPS satellites. Therefore, the accuracy of each satellite positioning device varies depending on the time even at the same place. In an environment with few multipaths, the accuracy can be compared using satellite arrangement information such as DOP (Dilution of Precision). However, since the number of multipaths increases in an urban area, the reliability of accuracy evaluation by DOP decreases. Even in such a case, according to the present invention, it is possible to evaluate the accuracy of each satellite positioning device and select position information detected by the most accurate satellite positioning system.

  Further, in this embodiment, the similarity of movement trajectories is used as an accuracy evaluation scale. However, in addition to this scale, it is also possible to evaluate using the similarity of the traveling direction data changing in time series and the similarity of the moving speed change.

  As described above, according to the present embodiment, the accuracy evaluation between the absolute position detection devices, which has conventionally been difficult to perform the accuracy evaluation, is performed using the similarity with the output trajectory of the relative position detection device as a determination criterion. be able to. For this reason, the position detection result calculated | required by the most accurate absolute position detection apparatus can be output as a position detection output. If it is determined that the accuracy of all available absolute position detection devices has deteriorated, select the detection output of the relative position detection device with the detected position as the initial position before the similarity decreases. By doing this, it is possible to detect the position with high accuracy by complementing the section in which the absolute position detection device could not detect the position.

It is a figure explaining the position detection apparatus concerning this embodiment. It is a figure explaining the process of a similarity calculation part, and the process of a position output switching part. It is a figure which shows the position detection result by GPS, and the position detection result by an inertial navigation apparatus. It is a figure explaining the similarity of a movement locus | trajectory. It is a figure which shows the example at the time of making a pedestrian carry a position detection apparatus. It is a figure explaining the example which made the threshold value at the time of switching an absolute position detection apparatus and a relative position detection apparatus variable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 GPS receiver 2 Wireless LAN position detection apparatus 3 Position detection apparatus by mobile phone base station 4 Infrared position detection apparatus 5 Inertial navigation apparatus 6 Display part 7 Relative position detection apparatus 8 Absolute position detection apparatus 9 Switching signal generation part 14 Similarity calculation Unit 15 Position output switching unit 10, 11 Communication device 12 Personal computer

Claims (2)

A plurality of types of absolute position detection devices that receive a plurality of signals radiated from known positions and detect their absolute positions;
A relative position detection device for detecting the amount of movement of the self within a predetermined period as a change in the relative position of the self;
A similarity calculation unit that calculates the similarity between the locus of the change in the relative position within the predetermined period and the change in the absolute position detected by the absolute position detection apparatus within the predetermined period for each of the various absolute position detection apparatuses. When,
Wherein among the plurality of kinds of absolute position sensing device, e Bei an output switching unit for selecting and outputting the output of the absolute position detecting apparatus having the greatest similarity,
When the similarity calculated by the similarity calculation unit is equal to or less than a preset threshold, the output of the relative position detection device with the detection output of the absolute position detection device immediately before the similarity is equal to or less than the threshold as an initial value Is a detection output of the position detection device, and the threshold value is decreased with time . A plurality of types of absolute position detection devices that receive a plurality of signals radiated from known positions and detect changes in their own absolute positions as trajectories, and detect changes in their relative positions within a predetermined period as trajectories A relative position detection device,
The absolute position detection having the maximum similarity by calculating the similarity between the locus of the change of the relative position within the predetermined period and the locus of the absolute position detected by the absolute position detection device for each type of the absolute position detection device. Select the output of the device and output it,
When the similarity is less than or equal to a preset threshold, the output of the relative position detection device with the detection output of the absolute position detection device immediately before the similarity becomes less than or equal to the threshold as an initial value is output as a detection output. The position detection method is characterized in that the threshold value is lowered over time .

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